Robotics

Spherebot is a variant of the Eggbot, which can draw on a spherical object like eggs, ping-pong balls, xmas baubles, etc.. The Spherbot uses an Arduino to control a servo and a couple of Stepper Motor Drivers.

Cyclone PCB Factory

The Cyclone a 3D Printable PCB milling machine developed in the same spirit as RapRap 3D printers. The hardware design is open and the community has contributed to its continuing development. Some useful resourses are the RepRap wiki and Thingiverse depot.

Components

Servos

HexTronik HTX90: (typ. £3.25 @ sparksid_rc)

A small (9g) servo motor with 1.6kg of force. Typical specs can be seen on the HobbyKing website.

Specs:

Size : 21x12x22 mm / 0.74x0.42x0.78 in

Voltage : 3v ~ 6v

Current : 750mA peak / 550mA avg.

Weight : 11g / 0.39oz

Speed : 0.12 sec/60(4.8V)

Torque : 2.5 kg-cm

Working Temp : -30C~60C

Gears : Nylon White type

Stepper Motors

17HS19-1684S: (typ. £12.50 @ Think3DPrint3D)

Popular bipolar (2 windings) motor with molex connector and plenty of torque for 3D printing.

Specs:

NEMA 17 (42 x 42 mm)

Bipolar, 4-wire

1.8 degree step angle

Holding torque 44 N.cm (4.4kg.cm, 62oz.in)

Voltage 2.8V

Current/Phase 1.68A

Weight 0.35kg

Stepper Motor Driver

Allegro A4988: (typ. £3.50 @ EllieShang)

DMOS Microstepping Driver with Translator and Overcurrent Protection, see datasheet.